1. Field of the Invention
This invention relates to a motor stator for a home electric fan, particularly to one reduced in its material used for the coil, and elevated in torque output and effectiveness of the whole motor.
2. Description of the Prior Art
A conventional home electrical fan (including an air exhausting fan, a cool fan, etc.) generally has a motor of a mouse-cage style stator for rotating a fan. The stator of the motor has structure shown in FIG. 1, consisting of a plurality of laminated silicon steel sheets 3 of the length and the width both 75 mm bored with a center hole 31 of a diameter 44 mm and a plurality of coil grooves 32 provided spaced apart around the center hole 31. FIG. 2 shows an upper view of the conventional motor stator 30 after combined with a rotor 5 located in the center hole 31 of the silicon steel sheets 3. Then the coils 4 are powered to produce a magnetic field to rotate the rotor 5 and subsequently rotate the fan. The specification of the conventional home electric fan with a four pole motor having 16 coil grooves has been made by makers for a long time, and still making up a main stream of conventional home electric fans.
Nevertheless, the conventional home electric fan always produces high temperature in operation, which seems to be caused by a large resistance of the copper coil, iron loss caused by reluctance loss, and excess current loss caused by magnetic field cutting after the motor is powered. These elements gives rise to the high temperature of the motor, and directly affects the output effectiveness of the motor.
An U.S. patent application of Ser. No. 09/527,884 filed on Mar. 12, 2000 has disclosed a motor stator for a hole electric fan designed to offer an improved motor stator having a plurality of silicon steel sheets having a center hole enlarged to 48 mm for an enlarged rotor to fit therein so as to try to lower the starting current of the motor, the temperature, the weight and the cost, but to elevate the effectiveness.
However, in realistic application, the best rotation rate of the motor rotor for a home electric fan is 950 rpm, far less than 1600 rpm (the standard of the conventional motor for a home electric fan), and too high speed of the rotation involves difficulty in realistic appliance and design of the motor for a home electric fan. As the conventional four-pole stator for the conventional motor for a home electric fan has a restriction of the coil grooves being 16 and the gap between the stator and the rotor so that the size of the center hole of the stator is impossible to be enlarged so as to meet the needed torque, potential reduction of the rotation rate by external condition such as a reversal wind, or unsmooth rotation of the motor rotor, which the U.S. patent application of Ser. No. 09/527,884 also has. Therefore, it has been a target for makers to offer a home electric fan having the needed rotation, high torque and low temperature.
This invention has been devised to offer a motor stator for a home electric fan, which has a plurality of laminated silicon steel sheets provided with a center hole of a larger size than that of the silicon steel sheets of a conventional motor stator for a home electric fan so that more coil grooves may be formed to increase the poles of the motor stator from four to six in order to meet realistic need and to strengthen torque for better operation.
The feature of the invention is the coil grooves being reduced in its size in contrast to the center hole enlarged so that the rings of the coil may be reduced and thus reducing the material needed for the coil and its rising temperature, and elevating its effectiveness.